This invention relates generally to a fuel control system for use in an internal combustion engine and, more particularly, to such a system which is functional independently of automatic choke and speed change mechanisms employed in the internal combustion engine.
Known are automatic speed change gears that automatically control conventional synchronous speed change gears in combination with a clutch mechanism. The automatic speed change gears are arranged typically such that a mechanical coupling between either a carburetor or a fuel injection pump is decoupled from an accelerator pedal and either a throttle valve or a control lever used as a fuel control device is driven by a stepping motor. Controlling the stepping motor is an electronic control unit that receives input signals both from a sensor that detects operation of the accelerator pedal and from a sensor that detects starting of the internal combustion engine and changes of speed thereof.
The fuel control device for the internal combustion engine that is controlled remotely as described above, is mechanically coupled to the stepping motor either directly or indirectly through a mechanical linkage. Such arrangements exhibit the following disadvantages. An automatic choke mechanism or a fuel increasing mechanism can not be employed generally to enhance starting of the internal combustion engine in cold weather. If they are used, the automatic choke mechanism or the fuel increasing mechanism can prevent proper functioning of the stepping motor. In addition, the throttle valve or fuel control valve cannot work properly as the accelerator pedal is pressed in normal driving.
It is an object of the present invention, therefore, to provide an improved fuel control system for use in an internal combustion engine.